Separable helper factors support B cell proliferation and maturation to Ig secretion.
The 24-hr culture supernatant of Con A-activated spleen cells (SN) contains helper factors that enable maturation to high-rate polyclonal Ig secretion and enhance proliferation in cultures of mouse B cells activated with the F(ab')2 fragment of class-specific rabbit antimouse IgM antibody (anti-Ig). When interleukin 2 (IL 2), also called T cell growth factor, is removed from SN by absorption with an IL 2-dependent cell line at either 4 degrees C or 37 degrees C, all the helper activity for anti-Ig-activated B cells is also removed. Partial removal of IL 2 results in partial removal of helper activity for B cells. However, the IL 2-depleted SN appears to contain another helper factor, TRF, that enables anti-Ig-activated B cell cultures to mature to high-rate Ig secretion. This TRF activity is revealed by adding purified human IL 2 or an IL 2-containing supernatant of a cloned, lectin-activated T cell hybridoma line (FS6-14.13) to Il 2-depleted SN, which restores the polyclonal antibody response to anti-Ig. The hybridoma supernatant by itself supports proliferation of anti-Ig-activated B cell cultures, as measured by an increase in cell number, but not maturation to Ig secretion. This proliferative response is likewise IL 2 dependent, although purified IL 2 with anti-Ig is not sufficient. These experiments define separable combinations of factors acting on anti-Ig-activated B cell cultures, one of which (SN) results in both proliferation and maturation to high-rate Ig secretion, whereas the other (hybridoma supernatant) results in proliferation only. IL 2 appears to be an essential component of both combinations, although the target cell for IL 2 action in this system remains to be determined.
D000042:Absorption; D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D000921:Antibody-Producing Cells / Q000276:immunology*; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007140:Immunoglobulin Fab Fragments / Q000276:immunology; D007375:Interleukin-1; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008297:Male; D051379:Mice; D008811:Mice, Inbred DBA; D011506:Proteins / Q000145:classification / Q000494:pharmacology*
D000888:Antibodies, Anti-Idiotypic; D007140:Immunoglobulin Fab Fragments; D007375:Interleukin-1; D007376:Interleukin-2; D011506:Proteins